The present invention relates to an endoscope, which includes an insertion portion to be inserted in a body cavity, and an operation portion for the folding and controlling thereof, having a connecting means for connecting a supplementary liquid injection means at the operation portion.
In one conventional endoscope, the distal end of a nozzle is directed toward an observation window, formed on the distal end of a portion for insertion into a body cavity, so as to clean the observation window by spraying it with cleaning water supplied through the nozzle from a water-supply pipe path extending inside the endoscope. In this way, any mucus or contaminant attached to the observation window can be easily removed. However, when this cleaning method is employed, the cleaning water cannot be sprayed at high pressure, and hence the observation window cannot be cleaned to the degree desired.
Japanese Patent Disclosure (Kokai) No. 58-175542 discloses an endoscope having a supplementary injection unit which communicates with a water-supply pipe path extending inside the endoscope. This supplementary injection unit includes a connecting means for connecting a high-pressure air injection means, such as a syringe, at the operation portion of the endoscope. This connecting means communicates with the supply pipe path which extends to a nozzle inside the endoscope. The injection means is connected to the connecting means, so as to supply high-pressure cleaning water to the nozzle, thereby to clean the observation window thoroughly.
The connecting means of the supplementary injection unit has a syringe mounting piece mounted in a water-tight fashion on the operation portion. The syringe mounting piece is fitted in a supporting cylinder and is inserted into a metal sleeve formed on a cover of the operation portion, and then pressed towards the inside of the operation portion by a fastening ring which is fastened to the metal sleeve on the supporting cylinder.
The above sleeve is made of a metal such as stainless steel, in order for it to have sufficient strength for supporting the fastening ring. In order to maintain the strength of the connection between the sleeve and the cover, these two parts must be connected not by simple adhesion, but by a high-strength method such as brazing. Therefore, the cover must be made of the same type of metal as the sleeve.
Nowadays, RF current treatment is very frequently performed by means of an endoscope. When RF current treatment is performed using the conventional endoscope, since the cover and the sleeve are made of metal, part of the RF current may leak through the cover and sleeve, thereby giving rise to the risk of injury to the operator (such as a doctor) through electric shock.
In order to prevent such a leakage of current, an endoscope has been proposed wherein the cover and sleeve are coated with a resist.
However, when the cover and sleeve are coated with a resist, part of the underlying metal surface may become exposed by paint peeling, damage, and the like, with the result that current may flow through this metal surface.